Cerebellar volumes reduced in bipolar I disorder patients
MedWire News: Patients with bipolar I disorder (BD I) have reduced left and right cerebellum volumes compared with mentally healthy individuals, suggest results from a Brazilian study.
"Since the 1960s, studies have posited that the cerebellum plays a role in the experience and regulation of emotion," write L Baldaçara (Universidade Federal de São Paulo) and colleagues in the Journal of Affective Disorders.
They add that previous studies have indicated cerebellar abnormalities in bipolar disorder patients, but the findings have been inconsistent.
To investigate further, and to evaluate the possible relationship between cerebellar volume and suicidal behaviour, the researchers studied 40 euthymic BD I patients and 22 mentally healthy controls of similar age, education level, and gender distribution.
Of the BD I patients, 20 had a history of suicide attempts. None of the participants had a history of neurological illness, head trauma, or substance abuse.
All of the participants underwent magnetic resonance imaging, and brain volume was measured using voxel-based morphometry. Patients with BD I were also assessed using the Structured Clinical Interview with the DSM-IV axis I, the Hamilton Depression Rating Scale, the Young Mania Rating Scale, and the Barratt Impulsiveness Scale.
The researchers found that were no significant differences in intracranial and overall brain volumes between the BD I patients and controls.
However, mean left cerebellum, right cerebellum, and vermis volumes were significantly smaller in BD I patients than controls, at 40.18 versus 44.31cm3, 41.15 versus 45.40 cm3, and 4.76 versus 5.62 cm3, respectively.
There were no significant volumetric differences between BD I patients with and without a history of suicide attempts.
There was also no significant correlation between cerebellar measurements and clinical variables among the BD I patients, the researchers note.
Baldaçara et al conclude: "Our findings suggest that the reduction in cerebellar volumes observed in BD type I might be a trait-related characteristic of this disorder.
"Additional studies with larger samples and subtypes of this heterogeneous disorder are warranted to determine the possible specificity of this cerebellar finding."
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By Mark Cowen